Parallel motion translation device for vibratory screens



April 21, 1953 A. J. ROUBAL. 2,635,752

PARALLEL MOTION TRANSLATION DEVICE FOR VIBRATORY SCREENS Filed March 20,1950 s Sheets-Sheet 1 A ril 21, 1953 A. J. ROUBAL 2,635,752

PARALLEL MOTION TRANSLATION DEVICE FOR VIBRATORY SCREENS.

Filed March 20, 1950 3 Sheets-Sheet 2 April-21, 1953 A.-J. ROUBAL2,635,752

PARALLEL MOTION TRANSLATION DEVICE FOR VIBRATORY SCREENS Filed March 20,1950 3 Sheets-Sheet 3 Will/1137777 2 Patented Apr. 21, 1953 PARALLELMOTION TRANSLATION DEVICE FOR VIBRATORY SCREENS Alexander J. Roubal,Milwaukee, Wis., assignor to Allie-Chalmers Manufacturing Company,Milwaukee, Wis.

Application March 20, 1950, Serial No. 150,650

This invention relates to the arrangement of screen surfaces onindustrial screening machines, and more particularly to mechanism fortensioning a screen section on its frame.

Material separating screens have long been known and various devices areknown for attaching screen cloth to a frame and applying tension theretoto create a firm screening surface. One manner of fastening a screencloth section to its frame is shown in C. S. Lincoln, U. :3. Patent No.2,338,523, involving metal strips of hook like cross section on oppositeends of a screen cloth section and engaging edge presenting crossmembers which are relatively movable to apply tension and thus preparethe screen for service. With the structure shown in the Lincoln patent,however, certain difiiculties have been experienced in tensioning screensections, particularly of screen sections intermediate the ends of thescreen deck. By the present invention applicant has made it possible tostretch or tension a screen cloth lengthwise of a screen deck frame withside Walls, like that of Lincoln, by merely operating a singletensioning nut located outside the side wall of the screen body, thusavoiding the difficulties experienced with previously known devices.

An object of the present invention is to provide a practical structurefor tensioning a screen cloth on a screen frame by operating a simplemechanism actuable from one side of the frame.

Another object of the invention is to provide a simple parallel motionmechanism for moving a screen tensioning bar in translation parallel toitself.

The invention resides in a novel mechanism for moving a straight barlike screen frame member in translation parallel to itself, relative tothe screen frame by actuation of a simple control member located at oneside of the screen side wall, and more particularly in the novelinstrumentality through which the desired motion is obtained.

Other objects will appear hereinafter as the description of theinvention proceeds.

The novel features of the invention and how the objects are attainedwill appear from this specification and the accompanying drawingsforming a part of this application, and all these novel features areintended to be pointed out in the claims.

In the drawings:

Fig. 1 is a side elevational view of a screen embodying the invention;

2 Claims. (Cl. 209--395) Fig. 2 is an end elevational view fromthedischarge end of the screen in Fig. 1;

Fig. 3 is an enlarged partial plan view of F1 1 looking in the directionof the line III--III with parts broken away and the screen cloth notshown to better show the construction;

Fig. 4 is a vertical sectional view taken on line IV-IV of Fig. 3 withthe screen cloth positioned in place;

Fig. 5 is a sectional view taken on line V-V of Fig. 3;

6 is an enlarged sectional view of the embodiment of the invention shownin Fig. 4; and

Figs. 7-10 are enlarged sectional views showing various otherembodiments of the invention.

Figs. 1 and 2 show as an example, a vibratory screen mechanism embodyingthe invention hereinafter set forth. The mechanism comprises sidemembers II vertically spaced parallel with respect to each other bytransverse frame members I2 to form substantially a rectangular frame.The frame is preferably suspended from roof trusses I3 by suspensioncables I4 secured thereto and to the side members I I. A vibratorydevice I5 is suitably located between the side members II on asupporting structure ll, toward the discharge end of the frame. Adriving motor I8 secured to cross beam I9 is connected to'drive thevibratory device I5 through such means, "as for instance a V-belt drivesystem 20. Vertical reinforcing angle bars 2| may be secured. to theside members II for increasing the rigidity of the frame. The screenmechanism herein shown comprises a two section top screen deck 23 and asimilar lower screen deck 24. Any number of screen sections and decks,however, may be employed within a practical limit for the particulartype of screening operation, but for the purpose of clearly showing anapplication of the invention to a vibratory screen mechanism, thestructure herein shown is adopted.

Referring more particularly to Figs. 3 and 4, the transverse framemembers I2 may be designated as feed end member 25, intermediate members26 and base members 21, in spaced parallel relation to each other. Thefeed end member 25 as well as one of the base members 21 in the case ofa two section screen, is provided with a hook-like element 28 forholding a hooked edge of a suitably hooked edged screen, such as aforaminous screen 30 of a known kind more fully described in U. S.Patent No. 2,338,523 .(supra), whereas the intermediate members 26 arepro vided with an upwardly projected element 3| for giving the propercontour to the screen surface.

inverted foot of L-shaped member 31.

3 The opposite hooked edge of the screen 30 is held by a motiontranslation device adapted to stretch the screen cloth 3!] on the screenframe as hereinafter described.

The motion translation device is essentially a means for convertingstraight line motion in one direction to straight line motion in anotherdirection to tension the screen cloth 30. Such a device is carried byeach of the base members 21 and comprises a screen holding element 32with a free edge spaced substantially parallel to a flat surface 33 ofor comprising a portion of the base member 2'1, which surface in turn isparallel to the general plane of the screen frame. The screen holdingelement 32 is connected to the base member 2? by guide means 34interengaged for the displacement of the screen holding element in adirection longitudinally relative to the screen frame. Fig. 5 shows theguide means 34 as comprised of two L-shaped members 36, 37 securedrespectively to the screen holding element 32 and the base member?! or aportion thereof as hereinafter more specifically described. A smallamount of clearance is allowed between the foot of the L-shaped member36 and the flat surface 33 to assure support of the screen holdingelement 32 on the Follower elements 38 project from the screen stretcherbar 32 at spaced intervals toward the base member 21 in various ways aswill more clearly appear in the specific embodiments hereinafterdescribed, and fixed longitudinally with respect thereto extend towardthe screen stretcher bar 32 above the flat surface 33 at a substantiallyuniform elevation. Mechanical means, such as wedge means 46 having alaterally inclined surface 4|, are interposed between the flange means39, and each follower element 38 within the space defined by the flatsurface 33 and the screen stretcher bar 32. the side wall ll towardwhich they are displaceable, and tangentially engage the elements 38 toimpart to the screen stretcher bar 32 a force having components in twodirections at right angles to each other. as a pullrod 42 is secured tothe wedge means 40 and longitudinally abuts the flange means One end ofthe pull rod 42 extends approximately to the center of the entire widthof the screen frame, and the opposite end extends through an opening inthe side wall II for manipulation outside the side wall. 7 7

Assuming that one hooked edge of the foramv inous screen 30 is held inthe hook like element .28, secured to the feed end member 25, and theopposite hooked edge of the screen is held by hooked engagement with thefree edge of the screen stretcher bar 32 carried by the base member 21,the desired degree of tension maybe placed upon the screen by urging thepull rod 42 laterally relative to side wall Ii as by adjustment meanssuch as a nut 44 threaded to the portion of the pull rod extendingbeyond the side wall. The wedge means 49 are simultaneously movedlongitudinally of flanges 39 to effect transmission of forcelongitudinally and laterally to the stretcher bar 32 through engagementof their inclined surfaces 4| with the fol-,

:lower elements 38. The engageable guide means however, restricts motionof the screen The inclined surfaces 4| face An actuator means suchstretcher bar 32, to a path longitudinally of and parallel to the sideplates H and transversely toward and away from the ridge or flange means39. It is hence evident that the tension on the screen 39 may be easilyvaried from a position outside of the screen frame proper, thus0bviating the difficulties heretofore experienced in prior screentensioning means.

Fig. 6 more clearly illustrates the structural embodiment of theinvention shown in Fig. 4 in which the base member 21 is constructed, asshown, as a hollow beam of rectangular cross section secured to shortsteps or brackets 45 of the side walls II. An elongated angle barelement 46 provided with legs 48, 49 embraces the base member 2! withinits included angle. This element 46, by means of leg 49, and the hooklike element 28 are secured to the base member 2'! by bolts 59 passedlaterally therethrough. The uppermost surface of leg 43 forms the flatsurface 33 of the screen stretching or motion translating devicepreviously described. Flange means 39 and the L-shaped member 31 of theguide means 34 are secured to this surface 33.

Elements shown in Figs. 7, 8, 9 and 10 similar to those in Fig. 6 aredesignated by the same reference characters with the addition ofrespective suflix letters a, 19,0 and d.

Fig. 10 is structurally similar to Fig. 6, except that the hook likeelement 28d is not provided with a bolt receiving portion by means ofwhich it could be bolted to the base member 21d, and instead is securedto the corner edge of the elongated element 6601 as by welding. Inaddition, the screen stretcher bar 32d is provided with a fixedlongitudinal shoulder 5| depending therefrom toward the surface 33d. Asealing strip of resilient material 52 abutting the shoulder 6| isdisposed between the screen stretcher bar 3201 and the leg 48d forpreventing material from entering therebetween and causing an abrasiveaction on the surfaces of the contacting parts. The resilient strip 52is also provided with a groove 54 for receiving an edge of the screenclothing, to effectively retain it in position.

In Fig. '7 the hook like element 280. is secured directly to the basemember 2'la. by means of bolts 56a. The construction differs from theembodiments shown in Figs. 6 and 10 in that the angle elements (46,.46d)of those embodiments is elim inated and the uppermost surface of thebase member 2111 forms the flat surface 33a. The flange means 3&1; istherefore secured directly .to the base member 21a by means of the bolts53a, and extends upwardly in alignment with one .side of the base memberabove the flat surface 33a toward the screen stretcher bar 32a. 7

The construction shown in'Fig. 8 shows a base plate 55 secured to thebase member 21b by means of bolts 59 to provide the fiat surface 33b towhich the flange means 397) and other elements'of the screen stretcherdevice are held.

The screen holding bar 32b is also shown as provided with a dependingshoulder 5!!) and a resilient strip 52?) similar to correspondingelements as shown in Fig. 10. The hook like element 2% inthis instanceis shown as'welded to an edge of the base plate 55.

Fig. 9 differs substantially from the previous embodiments in that thebase member 210 is comprised of elements performing two or morefunctions which as hereinbefore described were performed by separateelements.- In this instance flange means 390 is extended belowthe fiatsurface 330 to form an integral side of the hollow rectangular basemember 210, and extends transversely thereto above the flat surface toform a substantial support for the movable screen holding element 320.The flat surface 330 is formed on one sid eoi a hook plate 57 whichcomprises one side of the base member 2'80, and furthermore constitutesa portion turned upon itself for holding one edge of the screen clothing30c, heretofore secured to hook like elements 28, 28a, 28b and 28d.

The various structural embodiments shown in Figs. 7-40 are identical tothat of the embodiment of Fig. 6 as to the operation of the motiontranslating device as hereinabove generally described. Accordingly itwill be unnecessary to describe in detail the operation of eachstructural modification.

It will be obvious to those skilled in the art that the illustratedembodiments of the invention may be variously changed and modified, orthe features thereof, singly or collectively, embodied in othercombinations than that illustrated, without departing from the spirit ofthe invention, or sacrificing all of the advantages thereof, and thataccordingly the particular embodiments illustrated and described hereinare by way of example only, and the invention is not limited thereto,but is intended to include everything within the scope of the appendedclaims.

It is claimed and desired to secure by Letters Patent:

1. A screen cloth tensioning device for attaching a rectangular sectionof screen cloth to a vibrating screen frame having parallel side membersand transverse members connecting the side members, comprising: amovable screen cloth holding bar operably mounted on said frame so as toextend transversely between said side members, guide means operablydisposed between said frame and said screen cloth holding bar forguiding said screen cloth holding bar alon a, fixed path parallel tosaid side members, a pull rod operably mounted on said frame so as toextend transversely between said side members and so as to be movable ina transverse direction relative to said side members, follower means onsaid screen cloth holding bar, cam means on said pull rod cooperablyengaging said follower means in abutting relation for urging said screencloth holding bar to move along said fixed path parallel to said sidemembers when said pull rod is moved in a transverse direction relativeto said side members, and means for locking said pull rod in a selectedposition corresponding to the desired degree of tensioning of saidscreen cloth.

2. A screen cloth tensioning device for attaching a rectangular sectionof screen cloth to a vibrating screen frame having parallel side membersand transverse members connecting the side members, comprising: amovable screen cloth holding bar operably mounted on a transverse memberWhich connects said side members so as to extend transversely betweensaid side members, guide means operably disposed between said transversemember and said screen cloth holding bar for guiding said screen clothholding bar along a fixed path parallel to said side members, a pull rodoperably mounted on said transverse member so as to extend transverselybetween said side members and so as to be movable in a transversedirection relative to said side members, follower means on said screencloth holding bar, cam means on said pull rod having a surface inclinedrelative to said pull rod for cooperably engaging said follower means inabutting relation for urging said screen cloth holding bar to move alongsaid fixed path parallel to said side members when said pull rod ismoved in a transverse direction relative to said side members, and meansfor locking said pull rod in a selected position corresponding to thedesired degree of tensioning of said screen cloth.

ALEXANDER J. ROUBAL.

References Cited in the file Of this patent UNITED STATES PATENTS NumberName Date 25,256 Graham Aug. 30, 1859 1,518,236 Walcott Dec. 9, 19241,783,617 I-Iaselow Dec. 2, 1930 2,000,426 Symons May '7, 1935 2,139,089Linke Dec. 6, 1938 2,338,523 Lincoln Jan. 4, 1944 2,392,812 Faris Jan.15, 1946 FOREIGN PATENTS Number Country Date 12,039 Great Britain of1904 501,591 Great Britain July 19, 1939

